Ditches, walls, and palisades are extant in continental Europe from as early as the Neolithic, but important aspects changed in the course of the 2nd millennium BC. A review of the spectrum of dated sites from Central Europe shows that the expansion of metalworking techniques preceded the widespread occupation of high ground. Hill-top sites at crossroads and river crossings proved to be a permanent feature, though shifts in location occurred frequently. The motivation for the construction of walls and ramparts was probably not uniform. Certain walls were clearly built to be seen from afar. Hence, they can be explained as signs of presence and/or prominence. In other cases the aspect of enhanced security deserves special attention. The wide variation in size and regional settings of hill-forts as well as the divergent traces of occupation invalidate any unitary explanation.